Hydrostatically pressurized building foundation



HYDROSTATICALLY FRESSURIZED BUILDING FOUNDATION Filed March 30, 1967 Sheet l of 3 /N VEN TOR www@ 4 @Af/arma( Feb. 4, 1969 B. H. GERDE 3,425,175

HYnRosTATIcALLY PREssURIzED BUILDING FouNDAToN Filed Maron 3o, 1967 sheet 2. of z l AI8 *l B. H. @ERDE 3,425,175 HYDROSTATICALLY PRESSURIZED BUILDING FOUNDATION Feb. 4, 1969 Sheet Q -of Filed March 30, 1967 Bm/w AMJ/044W( United States Patent O 3,425,175 HYDROSTATICALLY PRESSURIZED BUILDING FOUNDATION Bernt Hialmar Gerde, Oktobergatan 6, Goteborg, Sweden Filed Mar. 30, 1967, Ser. No. 627,216 Claims priority, application Sweden, Apr. 5, 1966,

4,544/66 U.s. c1. 52--169 s claims Int. ci. Eozd 31/12, 27/01, 27/10 ABSTRACT F THE DISCLOSURE The present invention relates to a foundation in pairticular for great buildings and by means of the invention there is obtained a possibility of maintaining the subsoil water level constant around the building such that its foundation will be exposed toa constant pressure.

This invention relates to a foundation for buildings wherein liquid means are utilized for providing an upward pressure against the bottom slab of the foundation.

The foundation of buildings depends upon lground Iconditions generally in conventional methods using ground plinths, extended slabs, piling or special methods such as sink wells, caissons etc. With subsoil water, the level of this water is lowered permanently, e.g. by means of drainage or pumping or the lowermost building parts have been constructed watertight when such pumping was impossible.

The subsoil water level is very seldom constant but its height varies generally within wide limits depending upon atmospheric precipitation, the lwater penetrability of the ground etc. Further, the position of the subsoil water level is easily disturbed by excavating works, drainage measures, etc.

For this reason one can seldom take advantage of the lifting forces against the building part situated below the subsoil water level. Mostly the foundations and the base slabs of the buildings have to be dimensioned in such a way that (l) their own weight will be high enough so that there is obtained a security against rising when the subsoil water surface is at its maximum and,

(2) the foundation must be dimensioned with regard to the total weight of the building (its own weight and its charging load, etc.) when -the subsoil water surface is at its lowermost position and final-ly,

(3) the bottom slab must be dimensioned with regard to the maximum and the minimum subsoil water pressure.

An object of the present invention is to provide a construction for creating an upwardly directed water pressure against the foundation construction of a building and thereby take advantage of the reduction of the load obtained by means of this water pressure in upwards direction at the dimensioning of the foundation.

A further object of the invention is also to reduce or to equalize sinkings in the building while using the upward water pressure as an aid at the foundation, by cohesion piling, extended bottom slab, etc.

In the following specication and in the appended claims the expression water is used but is intended to cover any liquid suitable for the intended purpose.

ICC

In order to obtain the objects above the foundation construction of the building is made of a water tight material and a liquid supply or storage is arranged in the bottom slab of the foundation construction, said liquid storage being in communication with the space below the bottom slab. This space may be filled by macadam, pebbles, etc., closest under the bottom slab of t-he foundation construction. In order to limit the space in outward direction, this space is preferably enclosed by a watertight, downwardly directed sheeting or disk construction in watertight connection with the lower border of the watertight bottom slab.

When the space below the bottom slab and the liquid supply is filled with water, there is obtained a water pressure directed upwards against the bottom slab and a corresponding reduction of the foundation load of the order 1.0 metric ton per sq. meter for every meter of altitude with which the water level in the liquid storage exceeds the lower border of the bottom slab.

The Iwater level in the liquid storage will always be situated above the lower border of the bottom slab and it is determined to a suitable maximum position so that the building with a certain safety does not rise and oat on the foundation. However, the water level must not be so high that in case the watertight bottom slab or the liquid storage is destroyed by means of a deterimental influence, e.g. sabotage or war actions or the like, and the water is emptied from the liquid supply, the load increase thereby caused on the foundation will cause a rupture of the same. The water level in the liquid supply is kept within narrow limits so that there is obtained a precise and even upwards directed water pressure on the bottom slab such that the bottom slab has to Ibe dimensioned (its strength be calculated) only with regard to the upper water limit and will thus be independent of the water level, mostly the subsoil water level, in the ground surrounding the building.

There will occur a water stream between the water level of the liquid supply and the Water or subsoil water level surrounding the building, the direction of the water stream as Well as the size of the same will be dependent on the pressure difference, the water penetrability of the soil, the sheeting depth, etc.

So as to make it possible to maintain the water level in the liquid storage within the desired limits the storage is provided -with a device for feeding water to and from the same, e.g. by means of pumping, an overflow board, pressure valves, etc.

As a modication of the construction described in the aforegoin-g the liquid storage may be located outside the foundation wall of the building and this wall should comprise a watertight material and such as the excavating sheeting or a part thereof from the outer limitation of the liquid storage. The liquid storage may be put in communication with the space below the bottom slab of the building.

By dividing the space under the bottom slab of the foundation construction several sections with the water tight sheeting or disk construction and providing each section with its own liquid storage, there is obtained a possibility to provide different water pressures in the upward direction. When constructing buildings on uneven grounds or when utilizing building portions of different weights it is possible, by suitable control of the water pressure in upwards direction in the dilferent sections,

to counteract or to balance different settings of the building.

The invention will in the following be described in detail with reference to the accompanying, partly diagrammatical drawings showing some embodiments of the invention. In the drawings:

FIG. l is a partial cross section of a building level with the foundation level and provided with a liquid storage arranged in the watertight bottom slab,

FIG. 2 shows a partial cross section through a building level with the foundation level where a liquid storage is arranged at the side of the water tight foundation construction, and

FIG. 3 shows a plan view of a ground plot on which the buildings have been provided with foundation according to the invention.

Referring to FIG. l there is shown a first embodiment for the foundation of a building where the foundation wall 1 (the cellar wall) and the bottom slab 2 (cellar floor) are `constructed water tightly. It might be necessary to put down excavating sheeting 3 in order that the excavation of the ground down to the excavation bottom 4 may be carried out without any risk of falls. The excavation bottom 4 may be made hard, c g. by means of coarse concrete moulding or stabilization by means of mort-ar of lime.

Around the building circumference there has been lowered into the ground a watertight sheeting or disk construction 5 extending all around the 'building and thus enclosing the space 6 under the bottom slab 2. The sheeting 5 is watertightly connected with the bottom slab 2, being moulded in. In the space 6 under the bottom slab 2 there could be arranged a layer of filling material 7, e.g. coarse pebbles, macadam, or vthe like, which is shaped for giving a water penetration as good las possible and which extends under the whole of the bottom slab 2.

In the bottom slab 2 is arranged a watertight storage 8 in direct communication with the space 6 under the bottom slab 2. The filling material 7 may partly fill the liquid storage 8.

The space 6 under the bottom slab 2 :and the liquid storage 8 are filled with a liquid, preferably water, to a liquid level 9 for a suitable liquid pressure in upward direction against the bottom slab 2. In order to render possible a maintaining of the liquid level within narrow limits for level and thus obtain a well determined upward liquid pressure against the bottom slab 2, the liquid storage 8 is in communication, as indicated diagrammatically in FIG. l, through a tube conduit with a pump 10 controlled by a relay. If the liquid level 9 lowers to -below a determined minimum level 11, the pump 10 is connected for feeding liquid to the liquid storage 8 and in case the liquid in the liquid storage 8 rises up over a determined maximum level 12, the pump 10 is connected for discharging liquid. The maximum level 12 may also be controlled and ensured tby means of an overflow outlet 13 (brim discharge) and the overflowing liquid is gathered and discharged through a tube conduit to pump sumps.

The volume of the liquid storage 8, the maximum level 12 of the liquid and the minimum level 11 of the liquid, the depth of the sheeting 5, the capacity of the pump 10, etc., are determined while bearing in mind uctuations in the levels of the water and the subsoil water around the building and its pressure differences in relation to the level of the liquid in the liquid storage 8, the water penetrability for water in the soil, etc.

In FIG. 2 there is shown a partial cross section of a second embodiment of the invention where the foundation wall 1 (cellar wall) and bottom slab 2 (cellar floor) are likewise of a watertight construction. At the foundation there has been lowered into the soil an excavation sheeting 3 which at a certain distance surrounds the building and the ground is excavated around the building within this sheeting 3 down to the excavation bottom 4. The sheeting 3 or a portion thereof which is intended to form the outer limitation for the liquid storage 14 (the spacing between the sheeting 3 and the foundation wall 1) is made watertight.

In the space 15 below the bottom slab 2 there could be arranged a layer 16 of a material permitting the passage of water, this layer 16 extending under the whole of the -bottom slab 2 and partly up into the liquid storage 14. The space 15 under the bottom slab 2 and the water storage 14 is filled with a liquid, preferably water, to a level suitable for the upward liquid pressure against the bottom sla-b 2.

The water storage 14 is, also in this case through a tube conduit, connected to a pump 17 which is controlled by relays in such a way that the liquid level 18 is maintained within a predetermined limits, viz. the minimum level 19 and the maximum level 20. The maximum level can also in this case be ensured by means of an overliow outlet 21 (overflow discharge).

FIG. 3 shows how it is possible to surround a construction ground 22 by a water tight sheeting as indicated with broken lines 23 and then each building within this sheeting may be separated from neighbouring objects by means of watertight plates as indicated by means of chain lines 24. Further, each building object may as indicated in one case by means of double dot and dash lines be divided into sections 25, 26, 27 and 28. It is hereby rendered possible on the one hand to control the upward water pressure in each -building separately and on the other hand to expose every section in one and the same building to different upward pressure. Every building may thereby be individually adapted for an uneven load, uneven ground conditions, etc.

The control of the liquid level in the liquid storages may be carried out either from a common pump central for the whole building area or by means of a separate pump for each building or even for each separate section, 25-28, within the same building.

The invention has been described in the aforegoing for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims. Thus, the lateral limitation can of course be shaped in many different ways and be treated for being rendered water resistant. The liquid storage may also be shaped in many different ways and may be arranged anywhere in the celler (basement) where it may =be suitable with regard to other space requirements. The pump equipment may as obvious from the aforegoing be constructed arbitrarily within the scope of the invention as long as the equipment is such that it keeps the liquid level in the storage within the predetermined limits.

What I claim is:

1. A foundation for buildings and the like comprising a water-tight bottom slab having a space underneath the same, liquid storage means associated with said slab, means for controlling the liquid level in said storage means, means connecting said storage means with said space, water-tight means surrounding said space, said space containing a liquid permeable material which extends partly into said liquid storage means.

2. A foundation at set forth in claim 1 wherein said water-tight means surrounding said space is in water-tight connection with said bottom slab.

3. A foundation as set forth in claim 1 wherein said space is divided into sections by water-tight downwardly directed sheeting constructions.

4. A foundation as set forth in claim 1 wherein said liquid storage means is located at a side of said watertight bottom slab.

5. A foundation as set forth in claim 1 wherein said means for controlling the liquid level in said storage means comprises a pump and an overflow outlet.

(References on following page) Nicaise 52-303 Colgnet 52-169 Lane 52-169 Hartmann 52-303 Smith 52-302 Schneller 52-274 6 OTHER REFERENCES Wellpoint Team Dewaters Site While Recharging Surroundings, Construction Methods and Equipment, April 1956, PP. 74-76. Copy in Group 350.

HENRY C. SUTHERLAND, Primary Examiner.

U.S. C1. X.R. 

